Deflection circuits



Dec. 29, 1953 K. scHLEslNGER DEFLECTION CIRCUITS 2 Sheets-Sheet l Filed Nov. '7, 1951 INVENTOR Kun Sch/es Inger Dec.'29, 1953 K. scHLEslNGER 2,664,521

DEFLECTION CIRCUITS Filed NOV. 7, 1951 2 Sheets-Sheet 2 I JNVENTOR. Kur Schlesinger Patented Dec. 29, 1953 erica DEFLECTION CIRCUITS Kurt Schlesinger, Maywood, Ill., assignor to Motorola, Inc., Illinois Chicago, Ill'., a. corporation oi'v Application November 7, 1951, Serial No'.A 255,170

19 Claims. l

The present invention relatesv to television receiving circuits and more particularly to improvements` in the focus and deflection circuits of a television receiver;

Development research in the television receiver fleld has been directed towards circuit refinements which improve the quality of the reproduced picture and/or which improve the eniciency of the circuits While maintaining picture quality to thus reduce the number of circuit components. Recent developments. in the television industry have led to the use of larger direct view picture tubes and; the indications are that still larger direct view picture tubes. may be used. In order to keep the total length of the picture tube within reasonable limits and at the same time. increase the viewing sizey of. the picture the horizontal sweep angle has been increasedv to '10 or'more. Such wide sweep. angles, when applied to mod-1 ern tubes having relatively at viewing faces, result in a degradation of focus outside of the central viewing area normally encompassed by a sweep of 56 or so. Thus with respect to the horizontal. line structure of' the picture, the side portions of the picture are out of focus when the. central. area. ofthe picture is in. proper focus. To: correct such condition it would be necessary to. modulate, the focal. length of. the cathode beam in accordance with the horizontal sweep of the beam such thatV the focal length would beincreased when the beam. is. horizontally deflected t'owards'the side edges of the picture tube.

Horizontal deflection. circuits commonly in use employ a plurality or" stages including synchroni'zing signal stages, horizontal oscillator and driver stages. controlled. by the synchronizing signals, and theV horizontal sweep power output stage on stages.; ."Ln addition, the picture tube high voltage is usually. derived )from the horizontal deection circuits. lEtA isI desirable to reduce the number of tubesY and components, or circuit stages, without ailecting. picture quality.

The number of stages: in the amplifier circuits should not be reduced since this might impair sensitivity. Simplification of. the deflection circuits, on the other hand provides an excellent means of' reducing the complexity of a television receiverwithout impairing picture quality.

An object ofthe present invention is to provide an improved horizontal sweep circuit and focus control for. a television receiver.

Another object orthe invention is to provide an improved horizontal sweep circuit includingy a; self oscillating outputrstage that does not require a'lsepa'rate oscillator stage;

obtain horizontal' stability A furtherr object of. the invention is to provide a circuit for dynamically controlling the electron beam focus of the picturetube in accordance with the horizontal deilection of the electron. beam.

Still another object. of the invention is to provide a dynamic control of cathode ray focus length in accordance with the horizontal sweep signal, the; provision of the dynamic focus control further enabling the. use: of a self oscillating horizontal sweep power output stage.

A feature of this inventionv is the provision of a. horizontal sweep power output stage having controlled composite regenerative feedback which renders the stage self oscillating. In order to in the absence of syncnronizing signal pulses the composite feedback signal is formed of a pulse. signal derivedV from the pulse output of thel horizontal output,y tube combined with a sine wave signal derived from the horizontal deiiection coil circuit.

Animportant featurev of thev invention is the provision of a horizontal deflection systemy having a. resonant circuit tuned to the horizontal frequency coupled to the horizontal deflection coils, and which provides signals for dynamic` focusing of the cathode ray beam and also feedback for sustaining oscillations in the deflection system,

Another feature of the invention is the provisionof a focus system for a cathode ray tube including means producinga steady focus eld .and an auxiliary windingv supplied with varying focus current having a frequency of variation equal to the horizontal sweep frequency of the cathode ray and. related in: phase to the horizon.- tal sweep signal. such that the focal length of the cathode ray is. increased. for the maximum horizontal deflections of the ray to either side of its central position..

Still. another feature of the. invention is the system for providing a varying amplitude focus coil current inV an auxiliary dynamic focus coil winding connected. in series with the horizontal deection coil, and with the auxiliary focus coil Winding forming the inductance of a tuned circuit resonating at the sweep frequency to thus'provide a signal which maybe used as a component' of the composite regenerative feedback signall for the self oscillating sweep power output stage.

Further objects, features, and advantages of the invention will be apparent with reference to the following specication and the accompanying drawings, in which:

jFig. I is a schematic diagram of a self oscillating` horizontal sweep stage ofthe-invention hav'- i-ng a feedback circuit providing composite regenerative feedback;

Fig. 2 shows representative wave forms of the signals in various parts of the circuit of Fig. 1;

Fig. 3 is a combined schematic and diagrammatic View of a self oscillating sweep power output stage also providing dynamic focus of the beam of a cathode ray tube;

Fig. 4 illustrates another embodiment ofthe invention in which dynamic focus is provided;

Fig. 5 is a cross section of a focus coil including an auxiliary dynamic focus coil;

Fig. 6 is an exploded view of the focus coil shown in Fig. 5;

Fig. 7 is a combined schematic and diagrammatic representation of a self oscillating horizontal sweep power output stage coupled to a locked oscillator synchronizing stage; and

Fig. 8 shows an embodiment of the invention for use with an electrostatically focussed picture tube.

In practicing the invention a horizontal sweep power output stage of a television receiver is provided, and this stage is made self oscillatory by applying a regenerative feedback signal of the proper phase and wave form to the control grid of the tube thereof. Such power output tube is usually of the tetrode or pentode type. According to the invention, the feedback signal is a composite signal formed by the combination of a sawtooth voltage wave from the output circuit of the horizontal sweep output tube, together with a sine wave formed by a tuned circuit in series with the horizontal sweep deflection coil and resonating at the horizontal sweep frequency.

The tuned circuit in the feedback path assures stability of the sweep frequency and prevents tear-out in the absence of synchronizing signals. The resonant circuit for producing the sine wave regenerative feedback signal may be formed of a series tuned condenser and inductance connected in the return path of the horizontal sweep deflection coil so that the negative pulses occurring in the deflection circuit at the sweep frequency are transformed to sine wave potential variations of the proper phase for application as a regenerative feedback signal to the control grid of the self oscillating horizontal sweep power output tube.

To obtain dynamic focus control of the electron beam of the picture tube in accordance with the horizontally swept position of the beam, a focus control signal varying with a sine or co-sine variation at the horizontal sweep frequency must be applied to the picture tube in such manner as to dynamically control the focal length of the electron beam. Such dynamic focus signal is obtained according to the invention by means of the resonant circuit tuned to the horizontal sweep frequency and responsive to the horizontal sweep signal in the return path of the deflection coils. Such resonant circuit may be the same resonant circuit described in the preceding paragraph in connection lwith the formation of a sine wave component in the feedback signal vfor the sweep oscillator. The dynamic focus control sig* nal may be applied as either a varying potential for electrostatically focussed tubes or a varying current for magnetically focussed picture tubes. The inductance element of a resonant circuit coupled to the deflection yoke circuit may be used as a dynamic focus coil for varying the focal length of magnetic or electric lens of the picture tube. For example, an electrostaticall7 focussed picture tube may be provided with a small auxiliary dynamic focus coil secured on the neck of the tube in the vicinity of the electrostatic focussing lens and connected to the sweep circuit as previously described.

For a detailed description of the present invention, together with a specific disclosure of several embodiments thereof, reference is made to the drawings in which Fig. 1 shows a self oscillating horizontal sweep power output stage comprising the power output tube ID, horizontal sweep output transformer II and horizontal deflection coil windings I2 and I3. The return of the horizontal deflection signal to ground is interrupted by the condenser I4 and a. series resonant circuit consisting of the condenser I5, variable tuned inductance I6, and resistor I1. A regenerative feedback voltage having sine wave variations at the horizontal sweep frequency is thus developed in line I8 and applied through potentiometer I9 to the control grid 20 of the horizontal sweep output tube I0. A second regenerative feedback voltage consisting of sawtooth pulses at the horizontal sweep frequency is applied to the control grid 20 through the potentiometer I9 from the line 2l and condenser 2.2 connected to the output winding of the horizontal sweep output transformer Il.

The circuit as described in connection with Fig. 1 is self oscillating and has some of the features of a flywheel oscillator and therefore requires no separate oscillator. Referring to Fig. 2 of the drawings the sweep current circulating in the deflection coils I2 and I3 is shown by the curve 25 along with its fundamental sine Wave as shown by the dotted line curve 26. The series resonant circuit comprising the condenser I5, inductance I6 and coupling reactance I4 carries a circulating current as shown by the curve 21. If the coupling element I4 is a reactance as shown, the circulating current is a co-sine wave and is substantially out of phase with the sweep current fundamental waveform shown by curve 26. This current is therefore usable as a dynamic focus current in the circuits to be described in connection with Figs. 3, 4 and 7 of the drawings. The waveform of the composite regenerative feed# back voltage applied to the control grid 20 is represented by the curve 28. It is composed of a strong negative pulse portion 29 fed back through condenser 22 and potentiometer I9 and of a sine wave 30 as obtained in the ringing circuit comprising the condenser I5 and inductance I6. The sine wave 30 lags the fundamental component of the pulse wave 29 by 90 as is shown in Fig. 2. It should be mentioned that the strong negative pulse signal 29y is derived from the booster winding Ila and mixed with the ringing circuit by potentiometer IS in suitable proportions (about 1 to l) The addition of a ringing wave to the pulse feedback contributes materially to horizontal sweep frequency stabilization and noise irnmunity and thus to smoothness of vertical lines in the picture. The sine wave dei-mes the end of a line by passing through zero in a negative direction and it also locks several lines by virtue of resonance.

With reference to Fig. 3 a self sustained horizontal sweep oscillator circuit similar to Fig. 1- is shown in combination with a dynamic focus control for a picture tube. The sweep oscillator tube 35 is connected to the horizontal output transformer 35 through the efiiciency diode 39, and the high voltage rectifier tube 31 and its filter condenser 3B are provided to furnish high voltage for the picture tube 4i). The sweep oscil-N lator tube 35 is of the tetrode type having al. screen grid 4I and a control grid 42. The controlcoil 4B and condenser- 45 form a seriesv tuned circuity coupled to the. yoke circuit. by a condenser. 48., This coupling'element formsa ground return of. the sweep current through the deflection coil 4.5 which is in. turn connectedA toV the output winding of the horizontal sweep output transformer'S.

As` previously mentioned in connection with. curve. 2l of'Fig. 2, the circulating current. in the auxiliary focus coil.' winding 4E is of the desired phase to provide a dynamic control of the-focali length of the electron beam in accordance with the horizontally swept position of the beam.

'Ilhe phase relation of the current in the windping 4.6i with respect to. the fundamental.' of the sweep currentv (curve 26) may,. of course, be' controlled by the tuning ofY the resonant of ringing current. The arrangement of Fig.' 3 also provides an. additional feature in that the B plus supply `for the screen grid.. 4lof the. sweep oscillator tube 35 passes through a tuned circuit consisting of the inductance 50 and condenser-5| tuned to resonate at. the horizontal sweep frequency. The voltage appearing across the. tuned circuit consisting of the induotance- 59 and. condenser 5l is shown in curve 52. of Eig. 2 in relation tothe timing of the sweep current. The phase of the screen voltage so provided may be adjusted by the tuning. of the circuit. The secondV half of the wave. shown by the.- curve` 52` causes, the screen voltage to rise toward the end ofthe sweep pulse and producesa stretching eiect at theA right end of the picture: which tends to overcome a familiar type to sweep distortion. Referring to Eig. e. of the drawings a circuitis shown for providing a: dynamic focus control in connection with .a conventional forni of horizontal sweep amplier not having composite feedback and sustained oscillation features.. The. sweep amplier. tube (if) is connected to the horizontal sweeptransformerl 6l having an. eiiciency diode 62. connected thereto in; a conventional manner. The sweep outputV appears. across terminals. 63 and. 54 vand is connected to.V the horizontal denection coil 65 through condensers 65 and 61. A series resonant circuit consisting of thecondenser.

68, the auxiliary dynamic focus coil 69 and the.

rheostat 'lil are Iconnected in parallel. with the condenserl (il.` The vcirculating current.. througho oil 69 is then the. proper phase to provide dynamic focus control. as descrihedn connectionl with the curve'Z'I oflig; 2.

.Y Figs; and. 6 shown. some structuralfdetail of amodified magneticfocuscoilhavingvan auxiliary dynamic focus Winding therein.. The conventional focus coil` consists. of the metallic can 'l5 enclosing the magnetic pole '1.6, main focusy coil Winding Tl and magnetic. pole '18; Thev auxiliary dynamic focus winding is showny at I9 and the core sections of the magnetic pole 'I8 are cut baci: atl 8G to provide space for insertion of the aux-` iliary dynamic focus coil winding i9.. It should he noted that the. dynamic focus. coil winding A'I9 isfintfended to. apply auxiliary focussing effects on the electronbeain of the picture. tubewhich vary at the horizontal sweep ventiona-Ily 15,75) cycles per seconctf To form. an. auxiliary dynamic focus coil. winding which will.

frequency .which is. con.v`

chronization for weak. signals;

resonate eicently at the horizontal. sweep fre.- quency in a-.magneticstructure such. as the con.- ventional. magnetic focussing coi1 it is; necessary to copper plate the insidev of the magnetic poles 'lt-f and 18. and to slot the core portions of the pole 7.8;- inorder to reduce hysteresis losses at such relatively high frequencies as thehorizontal sweep frequency. The slotted; core portionsV of. the mage netio pole 'mare shown atgdl. 1

Referringfbackto Figs. 3 and 4 of the drawings it should beY pointed outv that each of the auxiliary focus` windings i6 andl 59, respectively, maybe emhodiecl in. a main focus coil structure such as described in connection with Figs. 5 and 6 of the drawings.

Inv connection with thev self oscillating horizontal. sweepY output circuits described in Figs. 1 and 3 of the drawings, it shouldI be mentioned that conventional synchronizing pulses asV obtained from the sync separator stages of the tele-'- vision receiver circuit may be applied to the control grid of the self. sustained sweep oscillator along with the composite regenerative feedback signal which has been described in detail. Such arrangement provides very satisfactory results and assures even horizontal line structure in. moderately strong signal areasand in the absence of any strong noise. signals. However', it will bey understood that the application. of synchronizing signals directly tov thev sweepl oscillator forms a circuit-thatis sensitive to noise signals forevery horizontal line in the structure of the picture. The arrangement showninlig.- 7 of the drawings. provides greater stability and horizontal .syn-

and. high noise levels. The circuit is in most. respects similar to that of'. Fig; 3 of. the drawings and those elements` of the` circuit which are identical and perform the same `function will begiven the same referencev numeral. and notv further described except asv necessary for an understanding of. this embodiment. Itlwill be noted-.thatthecontroi grid d2 of the sweep oscillator tube 35 is connected by the condenser to the plate electrode of. a locked oscillator tube 86. The control grid; and cathode electrodes of the locked oscillator tube 86 are connected in aA colpitts oscillator circuitm-odied to: be locked tothe frequency of the horizontalv synchronization pulses appearing through 'cone denser 81 from lthe horizontal sync separator: (not shown) of the television. receiver.` The ywheel effect of the locked oscillator tube 86 provides a ltered. and stabilized synchronizing signal to the sweep. oscillator. 35 which is'eectively protected from noise disturbance. For a. more detailed understanding of the operation of'a locked oscillator for television horizontal sweep synchronizationreference may be. made to the January 19,49 issue ot Electronics. pages `1.12- through 117..

The invention` thus far has been described int connectionA with applications for use with mag@- netically focussed picture tubes. Amodiiied formof. the inventionfor use with electro-staticyallyl focussed pictureftubes is sho-wn in. Fig. 8. ofthe drawings. A sweep yoscillator IUE is connected.' totheV horizontal output transformer HH. whose. output winding is connected to the, horizontal d'eilection coil m2. of the electrostatically focussed picture. tube to?. Ther return path of the sweep;

- current inv the deflection coil [02. is interrupted' by the` condenser IM and a series tuned circuit consisting of the condenser H35. and :the induci-y tancel las is connected acrossV the condenser m4; Theseries tuned circuitconsistng of the: con-- denser H35- and inductance |116y ist.. designed to resonate at'the horizontal sweep frequency and .the sine Wave voltage appearing across inductance |06 is connected by the resistor |08 as a regenerative feedback signal to the control grid |09 0f the sweep oscillator tube |00. Negative pulse feedback is applied through the condenser I and the resistor lll to the control grid |09 so that a composite regenerative feedback signal as previously described is provided to make the horizontal sweep amplifier circuit self oscillatory. An electrostatic focussing potential for the focussing electrode ||2 of the picture tube |03 is taken off the inductance |06 through coupling condenser The fixed focussing bias is taken from divider ||5 through high impedance resistor ||3, being bypassed by condenser H4. The varying voltage wave appearing across the inductance |06 is thus connected by the condenser ||1 to the focussing electrode ||2 of the electrostatically focussed picture tube |03 to thus provide a dynamic focus control in accordance with the horizontally swept position of the beam.

In the foregoing a self sustaining horizontal sweep oscillator circuit has been described, the arrangement being such that a composite regenerative feedback signal consisting of a pulse and a sine wave is used to obtain good stability of sweep frequency and phase. The invention has also disclosed an arrangement for providing a dynamic control of the focal length of the electron beam of a picture tube in accordance with the position of the beam. The circuit elements providing the dynamic focus control are also used to provide a sine Wave component for the feedback voltage in the sweep oscillator. Variations of the invention have also been described to show the application thereof for use with the electrostatically focussed picture tubes. It is to be noted that an auxiliary dynamic focus coil may be used with electrostatically focussed tubes in which case the steady focus is provided by an electrostatic field and the dynamic focus by an electromagnetic field. The dynamic focus may also be used in systems in which the steady focus is provided by a magnetic eld produced by permanent magnet structure. The combination of the self oscillating sweep circuit with locked oscillator synchronizing signal circuits, where difficulties from high noise and low signal levels may be encountered has been found to provide highly stable synchronization with a minimum of equipment.

It should be obvious that many variations of the invention may be made without departing from the spirit of the invention and the scope of the appended claims.

I claim:

1. In a television receiver having a cathode ray picture tube, a self oscillating horizontal sweep power output stage including in combination, a horizontal sweep power output tube having control grid and plate electrodes, a horizontalsweep output transformer connected to the plate electrode of said tube, said transformer having out put terminals, horizontal deflection coil means for deflecting the ray of said picture tube, a resonant circuit tuned to the horizontal sweep frequency, means connecting said resonant circuit and said deflection coil means in series across said output terminals, a first regenerative feedback path .connecting the pulse voltage in said transformer to said control grid of said tube, and

a second regenerative feedback path connectingy the sine wave voltage developed in said resonant. circuit .to said control grid of said tube to thus provide a composite regenerative feedback and cause the 'output stage to be self-oscillatory.

2. In a television receiver having a cathode ray picture tube, a self oscillating horizontal sweep power -output stage having, in combination, a horizontal sweep power output tube including control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, said transformer having output terminals, horizontal deflection coil means for providing horizontal deflection of the cathode ray of said picture tube, a resonant circuit tuned to the horizontal sweep frequency, said resonant circuit and said deflection coil means being con-` nected in series across said output terminals, a regenerative feedback ycircuit including a rst path connecting the pulse voltage in said trans# former to the control grid of said tube and a. second path connecting the sine wave voltage developed in said resonant circuit to the control grid of said tube, said resonant circuit being adapted to form a magnetic focussing eld adjacent the beam of said picture tube which varies with the current developed in said resonant circuit to thereby provide a Variation of focal length of the beam of said picture tube in accordance with the horizontal position thereof.

3. In a television receiver having a picture tube, a horizontal sweep power output stage having in combination, a horizontal sweep power output tube, said tube having control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, said output transformer having output terminals,- horizontal deection coil means for said picture tube, a resonant circuit tuned to the horizontal' deflection frequency, said resonantv circuit and said deflection coil means being connected in series across said output terminals, means applying the sine wave current developed in said resonant circuit to modify the focus of said picture tube to thereby provide a variation of focal length of the electron beam of said picture tube in accordance with its horizontally swept position.

4. In a television receiver having a picture tube,

a self oscillating horizontal sweep power output stage, including in combination, a horizontal sweep power output tube, said tube having control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, said transformer having output terminals, horizontal deflection coil means for said picture tube, a resonant circuit tuned to the horizontal sweep frequency, said resonant circuit and said deflection coil means being connected in series across said output terminals, a first regenerative feedback pathv connecting the pulse voltage in said transformer tothe control grid of said tube, a second regenerative feed-back path connecting the sine wave voltage developedin said resonant circuit to the control grid of 'said' tube, said resonant circuit comprising a coil and a condenser, said coil being arranged as an auX-' iliary focus coil for said picture tube whereby the current developed in said coil is effective toA provide a variation of focal length of the elec? tron beam of said picture tube in accordance withvv its horizontally swept position.

5. In a television receiver having a picture tube, a horizontal sweep power output stage, in -f` cluding in combination, a horizontal sweep powery output tube, said tube having control grid and;

plate electrodes, a horizontalsweep output trans' former connected to the plate electrode of saidA acess-2i tube, said transformer having `output terminals, horizontal deflection coil means for said .picture tube, a resonant circuit tuned to the horizontal sweep frequency, said resonant circuit and said deiiection 'coi-l means being connected in series across said output terminals, said resonant circuit or'nprising a coil and a condenser, 'said coil being arranged as an auxiliary focus coil for said picture tube whereby the sine wave current Vde veloped in said coil pro-vides a variahon in focal length in the electron beam of said picture tube in accordance with its horizontally 'swept posi'- tions 6. vIh a television receiver having an electro'- statically focussed picture tube with a focussing electrode, a self oscillating horizontal sweep power output stage, including in Combination, a horizontal sweep power output tube, said tube having control grid and plate electrodes, a horrzontal sweep output transformer connected to the pite 'electrode of said tube, said transformer having output terminals, horizontal deflection coil means for said picture tube, a resonant circuit tuned to the horizontal sweep frequency, said resonant circuit and said deflection coii means being 'connected in series across said output terminals, a first regenerative feedback path connecting the pulse voltage in said transformer to the control grid of said tube, a second reg-enerative feedback path connecting` the sine wave voltage developed in said resonant circuit to the control grid of said tube, means connecting the voltage vdeveloped in said resonant circuit to the focussing electrode of said picture tube to thereby provide 'a variation of focal length ci the electron beam of said picture tube in 'accordance with its horizontally swept position.

7-. In a television receiver having an electrostatically focussed picture tube with a focussing electrode, a horizontal sweep power output stage having in combination, a horizontal sweep power output tube, said tube having control grid and plate electrodes, va horizontal sweep output transe former connected to the plate electrode of said tube, said transformer having output terminals, horizontal deflection coil means for said .picture tube, a resonant circuit tuned to the horizontal sweep frequency, said resonant circuit and said deflection coil means being connected in series across said output terminals, means connecting the sine wave voltage developed in said resonant circuit to the focussing electrode of said picture tube to thereby provide a variation of focal iength of the electron beam of said picture tube in accordance with its horizontally swept position.

8. In a television receiver having a picture tube, a self-oscillating horizontal sweep power output stage including in combination, a hori zontal sweep power output tube, said tube havL ing control grid land plate electrodes, a horizontal sweep output trasformer connected to the plate electrode of said tube, said transformer having output terminals, horizontal dei'ection coil ineans for said picture tube, a resonant cir-- cuit tuned to the horizontal sweep frequency, said resonant circuit and said deflection coil es being connected in series across Said output terminals, a first regenerative feedback path for the pulse voltagepin said transformer, a second regenerative feedback 'path for the sine wave voltage `developed in said resonant circuit, means to combine in variable proportions said first and second regenerative feedback paths, and means to connect the proportionally combined re*- geeative feedback paths to the control grid of said tube and cause the output stage to be self oscillatory.

9. Ina television receiver having a picture tube, a yself-oscillatirig horizontal ysweep output stage, including in combination, -a horizontal sweep power output tube, said tube having `control vgrid and plate electrodes, Aa horizontal Asweep output transformer connected to the plat-e electrode of said tube, said transformer having output termi-'- nals, horizontal deflection coil means for :said picture tube, a vresoizlant circuit tuned to the 'horie zontal sweep frequency, said resonant circuit and said deflection coil means being connected in 'ses ries across said output terminals, a 'first 'regenera tive feedback path connected tothe pulse voltage inthe output 'winding of said transformer, a sec# ond regenerative feedback path connected to the sine wave voltage 'developed in said resonant circuit, 'means 'to combine in variable proportions Said first and second regenerative feedback .paths and to connect the combined regenerative feed; back paths to the `control grid of 'said tub'e,n'1eans applying the sine wave current developed in said resonant circuit being to modify the focus of said picture tube to thereby provide a variation of focal length of the electron beam of said picture tube accordance with 'its horizontally swept po'i sition.

l0. In a television receiver having a picture tube, a selfeoscillating horizontal sweep power output stage, including in combination, a horizontal sweep output tube, said tube having 'corr-'-` trol grid fand plate electrodes, a horizontal sweep output transformer connected to the Splat'e elec; trous of said tube, said transformer having output terminals, horizontal deflection coil means for said picture tube, a resonant circuit tuned to the horizontal sweep frequency, Said resonant circuit and 'said deflection coil 'e'an's being connected in Series across `Said output terminals, a first regen-- erative feedback pa'th 'connected to the pulse 'volte age in said transformer, a regenerative second feedback' path connected to the eine Wave volt'- ag developed n said resonant circuit, means to combine `in Variable proportions Said first and seo ond regenerative feedback paths, lmeans to con# neet the combined regenerative fe" 'dback paths to th control grid of said tube, said resonant cir; cuit comprising a coil and a c'ohdenser,lsaid coil being arranged as an ausiliari? focus coil for Said pioture tube whereby the 'sine wave current de vloped in saidoo'il provides a variation of focal length of the electron beam of said picture tube in accordance with its swept position. l

11; In a television receiver" having an electrolstatieally focussed picture tube with a focussing electrode, a self oscillating horizontal sweep power output stage, including invcombinatio'n, a lior-lzontal sweep power output tube, said tube hav'irc,r control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, 'said transformer having output terminals horizontal sweep deflection coil means for lSaid picture tube, 'a resonant circuit t'ue to the horizontal sweep frequency, Said r'es-l Ona-'rit cioul and said decton `Coil 'means being conneena 'in series across said output terminals, a rst regenerative feedback path connected to the pulse` vonage in said transformer, asecoau regenerative feedback path connected to the sine wave voltage developed in said resonant circuit, means to combine in variable proportions the feedback voltages in said rst and second feed; back paths, 'means to connect the combined feedback voltages to the control grid of said tube,

means connecting the sine wave voltage developed in said resonant circuit to the focussing electrode of said picture tube to thereby provide a variation of focal length of the electron beam of said picture tube in accordance with its horizontally swept position.

12. In a television receiver having a picture tube and synchronization pulse separating circuits, a self oscillating horizontal sweep power output stage having in combination, a horizontal sweep power output tube, said tube including control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, said transformer having output terminals, horizontal deflection coil means for said picture tube, a resonant circuit tuned to the horizontal sweep frequency, means connecting said resonant circuit and said deflection coil means in series across said output terminals, a first regenerative feedback path connecting the pulse voltage in said transformer to the control grid of said tube, a second regenerative feedback path connecting the sine wave voltage developed in said resonant circuit to the control grid of said tube to thus provide a composite regenerative feedback and cause the output stage including said tube to be self oscillatory, and means to apply the synchronization pulses from said synchronization pulse separating circuits to said control grid to control the oscillations of said output stage in accordance with said synchronization pulses.

13. In a television receiver having a picture tube and synchronization pulse separating circuits, a self oscillating horizontal sweep power output stage, including in combination, a horizontal sweep power output tube, said tube having control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, said transformer having output terminals, horizontal deflection coil means for said picture tube, a resonant circuit tuned to the horizontal sweep frequency, said resonant circuit and said deection coil means being connected in series across said output terminals, a first regenerative feedback path for the pulse voltage in said transformer, a second regenerative,

feedback path for the sine wave voltage developed in said resonant circuit, means to combine in variable proportions said rst and second regenerative feedback paths, means to connect the proportionally combined regenerative feedback paths to the control grid of said tube and cause the output stage including said tube to be self oscillatory, and means to apply the synchronization pulses from the synchronization pulse separating circuits to said control grid to control the oscillations of said output stage in accordance with said synchronization pulses.

14. In a television receiver having a picture tube and synchronization pulse separating circuits, a horizontal deection system including in combination a locked oscillator circuit having input and outputterminals, means for applying the synchronization pulses from said separating circuits to said locked oscillator so that said locked oscillator provides regularly spaced pulses in phase with said Synchronization pulses, a self-oscillating horizontal sweep power output stage includin`g,'a horizontal sweep power output tube having control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, said transformer having output terminals, horizontal defiection coil means for ,said picture tube, a resonant circuit tuned to 12 the horizontal sweep frequency, means connecting said resonant circuit and said deiiection coil means in series across said output terminals, a first regenerative feedback path connecting the pulse voltage in said transformer to the control grid of said tube, a second regenerative feedback path connecting the sine wave voltage developed in said resonant circuit to the control grid of said tube to thus provide a composite regenerative feedback and cause the output stage including said tube to be self oscillatory, and means coupling said control grid to said locked oscillator to control the oscillations of said output stage in accordance with the pulse output of said locked oscillator,

15. In a television receiver having a picture tube, a self-oscillating horizontal sweep power output stage including in combination, a horizontal sweep power output tube, said tube including control grid, screen grid, and plate electrodes, means connecting said screen grid electrode to a source of potential and forming a resonant circuit at the horizontal sweep frequency, a. horizontal sweep output transformer connected to said plate electrode of said tube, said transformer having outpui terminals, horizontal deflection coil means for said picture tube, a resonant circuit tuned to the horizontal sweep frequency, means connecting said resonant circuit and said deflection coil means in series across said output terminals, a first regenerative feedback path connecting the pulse voltage in said transformer to the control grid of said tube, and a second regenerative feedback path connecting the sine wave voltage developed in said resonant circuit to the control grid of said tube to thus provide a composite regenerative feedback voltage and cause the output stage including said tube to be self oscillatory.

16. In a television receiver having a magnetically focussed and deflected cathode ray picture tube, a self oscillating horizontal sweep power output stage, including in combination, a horizontal sweep power output tube, said tube having a control grid and plate electrodes, a horizontal sweep output transformer connected to the plate electrode of said tube, said transformer having output terminals, horizontal deflection coil means for said picture tube, focus coil means for said picture tube, said focus coil means having a primary focus coil winding and a second auxiliary focus coil winding, said focus coil means including copper plated pole pieces, said pole pieces having a portion thereof slotted to reduce hysteresis losses, a resonant circuit tuned to the horizontal sweep frequency, said resonant circuit and said deflection coil means being connected in series across said output terminals, a first regenerative feedback path connecting the pulse volt-v age in said transformer to the control gird of said tube, a second regenerative feedback path connecting the sine wave voltage developed in said resonant circuit to the control grid of said tube, said resonant circuit comprising said auxiliary focus coil and a condenser, whereby the sine wave current developed in said coil is effective to provide a variation of focal length of the electronv beam of said picture tube in accordance with its horizontally swept position.

17. In a television receiver including a magnetically deflected picture tube, deflection coilsv therefor adapted to receive a sawtooth current wave therein, and means for deriving synchro-` nization pulses for controlling the deflection pro.-

duced by the coil; a self oscillating horizontal de-M acarrear i3 dection output stage producing a sac/tooth current Wave haring trece i l portions including in con` .put tub includat le: trode, reetiier means, necting the deflection co and to said rectier ni s, salu. including inductance n' r3ans means tuned to the sonant circuit connectl said means for deriving a pui e voltage Ware there-- from with the pulses oscuri retrace portions oi said san-tc t .l

resonant ci a sine wave voltage tire n lags the undarnental component voltage wave by said feedback` circuit includ g a portion connected to a grid electrode of said tube for applying said pulse voltage and said sine wave voltage in cornbination thereto for sustaining oscillations in said tube, means for applying the synchroniaation pulses to a grid electrode of said tube ior synchronizing .said ose with.

18. In a television receiver including a niagnetically deflected picture tube, deflection coils therefor adapted to receive a sau/tooth current Wave therein, and means for deriving synchronization pulses for controlling the deflection produced by the coil; a self oscillating horizontal deflection output stage for producing a sawtooth current wave having trace and retrace portions including in combination, an output tube including a control grid electrode, a screen grid electrode, and a plate electrode, a source of potential, rectier means, a coupling circuit connecting the deflection coils to said plc te electrode and to said rectier means, said coupling circuit including inductance means and resonant circuit means tuned to the horizontal deection frequency, a regenerative feedback circuit including a first portion connected to said inductance means for deriving a pulse voltage Wave therefrom with the pulses occurring during the retrace portions of said sawtooth wave, said feedback circuit including a second portion connected to said resonant circuit means for deriving a sine Wave voltage therefrom which lags the fundamental component of said pulse voltage Wave by 90, said feedbtck circuit including a portion connected to said control grid electrode of said tube for applying said pulse voltage and said sine Wave voltage in combination thereto for sustaining oscillations in said tube, second resonant circuit means tuned to the horizontal deflection frequency connecting said screen in d uctance ions in tube therem "ifi grid to said source of potential, and means for applying the synchronization pulses to said con trol grid electrode of said tube for synchronizing oscillations in said tube therewith.

19. In a television receiver including a mag netically deiiected picture tube, deflection coils therefor adapted to receive a sawtooth current Wave therein, and means for deriving synchronization pulses for controlling the deflection produced by the coil; a self oscillcting horizontal deflection output stage for producing a sav/'tooth current Wave having trace and retrace portions including in combination, an output tube including at least one grid electrode and a plate electrode, rectifier means, a coupling circuit connecting the deflection coils to said plate electrede and to said rectifier means, said coupling circuit including inductance means and resonant circuit means tuned to the horizontal deflection frequency, said resonant circuit means including condenser ineens and dynamic focus coil means connected in series with said condenser means applying a voltage to said focus coil means, a regenerative feedback circuit including a rst portion connected to said inductance means for deriving a pulse voltage wave therefrom with the pulses occurring during the retrace portions of said sawtooth Wave, said feedback circuit including a second portion connected to said focus coil means of said resonant circuit means for deriving a sine wave Voltage therefrom which lags the fundamental component of said pulse voltage Wave by 90, said feedback circuit including a portion connected to a grid electrode of seid tube for applying Said pulse Voltage and said sine wave voltage in combination thereto for sustaining oscillations in said tube, and means for applying the synchronization pulses to a grid electrode of said tube for synchronizing said oscillations in said tube therewith.

KURT SCHLESINGER.

Reierences Cited in the file 0f this patent UNITED STATES PATENTS Number Name Date 2,220,303 Tingley Nov. 5, 1940 2,543,305 Schwarz Feb. 27, 1951 2,545,346 Edelsohn Mar. 13, 1951 2,584,213 Longo et al Feb. 5, 1952 OTHER REFERENCES Rider llelevision Manual, vol. 3 Bendix pages 3-28. (Copy in U. S. Patent Ofce Scientific Library.)

Electronics Jan. 1949, pp. 112-117. (Copy in U. S. Patent Oice Scentic Library.) 

